Exhaust gas treatment



glwvntow y attozmqn T. A. BOYDET AL EXHAUST (ms TREATMENT Filed Aug. 13

March 8, 1932.

Patented Mar; 3, 1932 UNITED s'raras PATENT; OFFICE THOMAS A. BOYD, WHEELER G. LOVELL, D JOHN H. CAMPBELL, O! DETROIT, MICHI- GAN, ASSIGNORS T GENERAL MOTORS RESEARCH CORPORATION, 01' DETROIT, MICHIGAN, A CORPORATION OF DELAWARE EXHAUST GAS TREATMENT Application filed August 18, 1927. Serial No. 212,710..

This invention relates to a device for the treatment and disposal of exhaust an internal combustion engine.

The exhaust gases that are discharged from most internal combustion engines as they are operated today, especially in motor vehicles, include carbon dioxide, carbon monoxide, hydrogen, water vapor, partially oxidized hydrocarbons, and occasionally some free carbeen proposed to eliminate them by bon. Among the constituents just enumerated, carbon monoxide and partially oxidized hydrocarbons are particularly undesirable, the former because it is harmful to animal life, and the latter, because of unpleasant 0 or.

Inasmuch as both of these types of undesirable constituents are combustible, it has nixing the exhaust gases with the proper amount of air, and burning the resulting mixture, thereby producing an exhaust gas that isodorless and harmless. As a general rule, the exhaust gases from automoblle engines contain such a small amount of combustible matter that, at the temperature the gas assumes after it has been exhausted from the engine and been mixed with a suitable amount of air, combustion will not support itself, because the amount of heat generated in the combustion is not large enough toheat succeeding portions of the gas to its kindling or ignition temperature. It has been shownthat the limit of inflammability' of a gas that is lean iii-combustible is dependent uponthe magnitude of its initial temperature. Thus, for

instance, a mixture which will not support combustlon at ordinary temperatures, may be easily combustible at a-higher temperature, after it has been ignited by some suitable means such as an electric spark. The problem in connection with the burning of exhaust gas,- therefore,*is to bring the initial temperature of the air -and gas mixture to a I point that is high enough for combustion to support itself, whereupon the flame will rapidly proceed through the mixture after it has once been initiated. 4 I

It has been proposed tomix the exhaust gases with. air close to the engineso-that as little as possible of the-heat of the primary gases from combustion will be lost. Aside from the dif- .ficulty of locating the secondary combustion chamber closely enough to the exhaust to take the maximum advantage of the heat from the engine, the coolingefiect of the air mixed v therewith is-such that combustion does not occur properlg. I i

In the wor 'n out of a device that, would accomplish the esired result, we have ai -med to incorporate'into it five basic elements of 6 construction, as follows:

(1) A means for pre-heating the raw air by exchange of heat with the waste gases leaving the burner. I

(2) A meansfor getting the air and exhaust gas thoroughly mixed before i ition.

(3) A means for further heating t e mixture of air and exhaust as by exchange of heat with the hot burned gases.

(4) A means for igniting the combustible 7o mixture. y

(5) Provision for the combustion chamber to be of a size suflicient to insure complete combustion within the burner.

' The counter current principle of heat ex- 76 change has been embodied in our invention in. order that the incoming gases may be heated to just as high a temperature as possible before 'enterin the chamber where they are burned. It is important to obtain the very highest possible temperature iii the combustion chamberin order to burn gases'which are quite lean in combustible. This high temperature is secured in our invention by making the combustion chamber the inner most part of the burner';.so that the combustion chamber is'almost entirely surrounded by a number of annular s aces through which flow hot incoming gases, ot out-going gases, and warm air, respectively, naming in order from the inner space to'the outer space. I

v In the use of this structure, it may be dea be shut oil. In a device of this kind it may be desirable to place all the parts in close proximity to the engine, omitting the ignition element and relying solely on the heat,

from the exhaust for starting the second.- ary combustion.

We have designed this device having in mind especially the roblem of disposing of the exhaust from t e engine of a motorpropelled vehicle but we desire it to be ditinctly understood that it is not limited in its scope to a vehicle but may be used to good advantage with an internal combustion engine regardless of where used.

In the drawing:

Figure 1 is a longitudinal vertical section of our device, showing the construction of our secondary combustion chamber.

Figure 2 is a section taken on the line 22 of Figure 1.

Figure 3 is a section taken on the line 33 of Figure 1. I

Figure 4 is aperspective view of the closure member which may be adjusted to vary the amount of air which is permitted to enter the secondary combustion chamber.

Referring to the drawings, the numeral 10 indicates a portion-of the exhaust-pipe, which is the outlet for the exhaust gases from the engine, and normally extends rearward from the engine and under the body in the case of a motorvehicle. Connected to the exhaust pipe is the secondary combustion chamber, this term being used to disting'uish from the primary combustion chambers of the engine. proper. I

The secondary combustion chamber comprises the disk-shaped end member or casting 12 fixed to the exhaust pipe 10 in any desired manner, as by welding or by rivets or bolts (not shown). The end member 12 is provided with an enlarged or thickened central portion 14 having a threaded opening corresponding to the exhaust pipe 101and fixed in this openin is the stub pipe 16. Fitting over the mem er 12 is the outer cylindrical casing 18. Fitting over the enlarged por tion 14 of the end member 12, and fixed thereon as by welding. is the substantially coneshaped inlet or inlet chamber 20.. The inlet 20 is provided adjacent the enlarged portion 14 with circumferentially arranged apertures 22. Surrounding the inlet at this'point is the closure member 24 provided with apertures 26 corresponding in size and number to the apertures 22. The closure member 24 fits against the member 12 and isprovided with a diverging rear end for fitting against the cone-shaped portion-of the inlet 20, thus being held against longitudinal movement. The member 24 may be rotatably adjusted by means of a toothed rack' or segment 28 provided thereon and meshing with the pinion 3O fixed to 'the shaft 32. Mounted on the shaft 32 is an arm 34: which may be connected to any desired means (not shown) for anguwhich may be connected with the i lar adiustment. The rear end of the inlet 20 is provided with circumferentially spaced bent out poitions 36, three being shown, for

holding the inlet snugly in the casing 18.

Fitting within the inlet 20 is a somewhat cone-sha d casting or conduit member 38 provide with three circumferentially arranged conduits 40. Bent out portion 42 are provided on the member 38 for fitting against the cone-shaped portion of the inlet 20. The flange 39 ofthe casting'38 completely closes the rear end of the cone-shaped inlet 20 except for the openings through the conduits 40. Fitting aroundthe outside of these conduits and welded thereto is the inner casing 44, which is providedwith spaced bent out portions 46 for holding it within the rear end of the inlet 20. Fitting within the rear end of the inlet 20 and slidable lon 'tudinally relatively thereto is the interme iate cylindrical casing which is fixed at its rear end by welding or otherwise, to the disk shaped rear end casting 54. Fixed within the rear ends-of the conduits 40 is the outlet cylinder 48 provided with spaced bent out portions 50 for holding the cylinder within the casing 44. By this arrangement it will be seen that the conduits 40 open directly into the annular space between the casing 44 and outlet cylinder 48. The forward entrance to this annular space is closed by bent out portions 52- of the cylinder 48, except inthe three sections corresponding to the conduits 40.

The rear end of the combustion chamber is closed by the rear end casting 54 in the center of which is fixed a casin 56 substantially the shape of a truncate cone. The forward portion of the casing 56 is cylindrical with a conical end and fits snugly and slidably within the inner casing 44. Fixed to the member 54 by bolts or otherwise is the outlet pipe 58.

The outer casing 18 is provided at its rear end with a bent out portion or flange 60. Bolts 62 connect the end member 54 and flange at spaced intervals about the periphery thereof, a coiled expansion spring 63 being placed about each bolt 62 between the flange 60 and the nut 64. In the center of the and member 54 is the ignition element 66. We have illustrated this as a spark plug ition system so that when desired a contmuous spark can be maintained across the spark gap. However, any other suitable i tion element may be used, such as an incan escent filament.

We thus provide a telescopic inner combustion chamber made up of two parts, the first comprising the inlet chamber 20 and casing 44 fixed rigidly therewith and a second element slidable longitudinall therewith and comprising the cone-shape end casing 56 fixed rigidly to the disk-shaped end membolts 62 connectmg the member 54 and the Durin- I ber 54. These two telescopic members are resiliently held together by the spring pressed outer casin 18 which is rigid with relation to the inlet chamber 20 and casing 44.

The operation of our device is asfollows:

the ex aust gases pass from the engine through the exhaust pipe '10 and throu h the stub pipe 16 into the cone-shaped in et 20. The central or neck portion of the inlet 20- is constructed as illustrated. The entering current of exhaust ases creates a suction at this point, as indlcated by the arrows, and air is drawn in throughthe openings. 22 and 26 from the space between the inlet 20 and outer casing 18, the free entrance of air to this space being permitted between the intermediate casing and outer casing 18.. The air thus entering is heated by passing over the intermediate casing 45 whlch is heated. by thehot burnt gases escaping- ,from the combustion chamber, as described below. The

preheated air enters through the openings 22 der 48 and on to the and 26 and mixes with the exhaust ases entering through the stub pipe 16. he mixturethen passes through the conduits 40 between the inner casing 44 and outlet cylinrear of the chamber adjacent to the spark plug, as indicated by The hot mixture is ignited by These burning gases pass out throng the outlet cylinder 48 and between the conduits 40 into the annular space between the inner casing44 and intermediate casin '45and out position which to allow for uneven com through the .outlet pipe 58, as mdicated by the, arrows. 'In case too much air is mixing with the exhaustgases, the closure member 24 maybe rotated by means of the arm 34and the effective size of the apertures adjusted .to the gives most eflicient operation. The spaced springs 63 expand and contract dumng operation of the device in order to permit the chamber to expand longitudinally ustion, limited expansion and contraction or telescopic movement being permitted'by the sliding contact of the various elements as described.

In starting the burner from the cold, it is usually necessary to choke the engine in order to providethe burner with exhaust gas that the normal operation of the engine,

from said chamber including roundin ate high temperature which is conducive to most complete oxidation of the unburntconstituents of the entering products of the primay or engine combustion chambers:

In case it is desired to burn a .very lean exhaust as, it may be necessary to surround the. entire urner with asbestos or with some other thermal insulating material that is suflicient- 1y heat resistant, in .orderto retain as much heat as possible within the burner.

We claim: i

1. In combination with an exhaust pipe, a device connected to the pipe for burning the combustiblegases in the exhaust gas of an internaleombustionengine com rising front and rear end" members, means or admitting air to the device a plurality of telescopic casings having their ends secured to said members, an outer casing rigidly secured to one member and resiliently and movably" connected to the other member, ,an ignition element in the innermost casing, means for delivering air from between the outermost casings to the innermost casing, and means for allowing the flow of gas from the inner casing between the two innermost casings to an openingin the rear end member. l 2. In combination with an' exhaust pipe, a device connected to the'pipe for burning the combustible gases in the exhaust gas from an internal combustion engine comprising an inner combustion casing or chamber, an ig nition element in said'chamber, an exhaust gas inlet to said chamber, an exhaust outlet a casing sursaid combustion casing, a casing surroun ing. said second namedcasing and defining a space ther'ebetween to allow for the ingress of air; and means for delivering the --air to the combustion chamber. I 3. In combination with anexhaust pipe, a device connected to the pipe for' burning the combustible gases in the exhaust gas of an intemal combustion enginecomprising' front and rear end members, means for admitting air to the device, a plurality of spaced telescopic casings having their ends secured to I said members, anaouter casing rigidly secured to one end member-and resiliently and movablyconnected to the other end member, an ignition element to ignite the combustible gas in the innermost casing, means for delivering air from between the outermost casings to the innermost casing, means for allowing the flo'w of gas from the inner easing into the space between the twoinnermost casings to an opening in the rear end member, and means to control the amount of air admitted to the inner casing. *4. In combination with an exhaust pipe, a

device connected to the pix for burmng the combustible gases in the e aust gas of an internal combustion engine comprising front and rear end members, means for admitting air to the device, three spaced telesco ic casings having their ends secured to sai mem- 'bers, an'outer casing rigidly secured to one member and resiliently and movably connected to the other member, an ignition ele-' ment to ignite the combustible gas in the innermost casing, means for delivering air from between the outermost casings to the innermost casing, and means for allowing the flow of gas from the inner casing into the space between the two innermost casings to an opening in the rear end member.

5. In combination with an exhaust pipe, a device for burnin the combustible gases in the exhaust gas roin internal combustion engines, consisting of a plurality of spaced concentric casings and chambers, end pieces rigidly connected to said casin s, an inlet from the exhaust pipe at one en piece to a first casing, an out et from a second casing at the other end tpiece, an ignition element to ignite the com ustible gas in the innermost casing, an outlet from said innermost casing directly to a second casing, and a passage between the outermost casings and an inlet to said first casing for delivering air to said first named casin 6. In combination with an exhaust pipe, 9. device for burning the combustible gases in the exhaust gas from internal combustion engines, consisting of a plurality of concentric casings and chambers the innermost casings comprising a plurality of relatively slidable parts, end pieces rigidly connected to said casings, an inlet from the exhaust pipe at one end piece to one casing, an outlet from a second casing at the other end piece, an ignition element to ignite the combustible as in the innermost casing, means to allow t e ingress of air to the device, and means to cause the air to How to the innermost casing.

7 In combination with an exhaust pipe, :1. device connected to'the pipe for burning the combustible gases in the exhaust gas from an internal combustion engine comprising an inner combustion casing and chamber, an ignition element to ignite the combustible gases in said chamber, an exhaust gas inlet to said casing, an exhaust outlet from said casing including a casing surrounding said combus tion casing, a casing surrounding said second named casing and defining an air passage therebetween, means for delivering the air to, the outermost of said casings com rising a single piece resiliently and movab y connected to one of said end pieces and rigidly secured to the other, an inlet from the exhaust pipe at one end piece and connected to a second casing, an outlet from said second THOMAS A. BOYD. WHEELER G. LOVELL. JOHN M. CAMPBELL.

' tures.

to the combustion chamber, end portions on I said device, said outer casing spaced from one of the end portions to allow for the ingres of air, and bolts and surrounding springs urging said outer casing toward said one end.

8. In combination with an exhaust pipe, a device for burning the combustible gases in the exhaust gas from internal combustion engines, consisting of a plurality of concentric casings, end pieces, each en piece having some of the casings rigidly connected there- 

